[451] Sort Characters By Frequency

算是偷吃步的一個方法(嗎)

寫的有一點醜因為一開始以為只有小寫字母

後來發現有大寫字母

再後來發現有數字嗎！

難怪別人都直接128的array 給它開下去Orz

修正版應該就是改成array 128吧但是現在有點忙啊XD

struct map {

int freq ;

char target ;

};

int comp(const void *a, const void *b)

{

struct map *m1 = *(struct map**)a;

struct map *m2= *(struct map**)b;

return (m2->freq - m1->freq);

}

char* frequencySort(char* s) {

struct map **array = calloc (62, sizeof(struct map*));

int len = strlen(s);

int i=0, j=0;

for (; i< 26; i++)

{

array[i]= calloc (1, sizeof (struct map));

array[i]->target = i+ 'a';

}

for (; i< 52; i++)

{

array[i]= calloc (1, sizeof (struct map));

array[i]->target = i-26 + 'A';

}

for (; i< 62; i++)

{

array[i]= calloc (1, sizeof (struct map));

array[i]->target = i-52 + '0';

}

for (int i=0; i< len; i++)

{

int idx = s[i]-'a';

if(idx <0)

{

if (s[i]-'A' < 0)

idx = s[i]-'0'+52;

else

idx = s[i]-'A'+26;

}

// array[idx]->target = s[i];

array[idx]->freq ++;

}

qsort((void *)array, 62, sizeof(struct map *),comp);

i = 0;

while(i<len)

{

while (array[j]->freq > 0)

{

s[i++] = array[j]->target;

(array[j]->freq)--;

}

j++;

}

return s;

}